"Hot as Sun" is an instrumental penned by Paul McCartney and included on his 1970 album McCartney coupled with the non-song "Glasses" (which also contained a snippet of "Suicide," another unreleased Paul McCartney tune). In that album's press release, Paul informs us that it was a "song written in about 1958 or 59 or maybe earlier, when it was one of those songs that you play now and then." The Beatles performed the song live from 1957 to 1959. They also resurrected the song during the Let It Be sessions (released on bootlegs) in January 1969. Paul later performed the song live with Wings in December 1979.
In 1978, "Hot as Sun / Glasses" was used as the theme tune to The All-New Popeye Hour. The original track was sped up, played at 45 rpm.
Tim Rice later added lyrics to the tune and it was issued as a single in July 1982 by Noosha Fox and also included on the Elaine Paige album of the same title in November 1982 (although the sleeve notes on Elaine's LP claimed that Paul had written the number specially for her).
In a fictional short story which appeared in Rolling Stone magazine around the time of the Beatles' breakup, "Hot as Sun" was a lost Beatles album, unreleased due to the theft of its master tapes.